Summary: In the rich mineral assemblage found in the pegmatites of Rhodesia and Uganda are members of the amblygonite-montebrasite series with α 1·592–1·615, γ, 1·612–1·638, the highest values corresponding to montebrasite, Li_1·98Al_2·00 (P_1·95O_7·90)(OH_1·90F_0·20); apatite with up to 8·8 per cent MnO; heterosite (new analysis) and other manganese-iron phosphates; and a variety of niobium-tantalum and uranium minerals.